A combination of flow cytometry and traditional screening using chemicals to isolate high glutathione-producing yeast mutants.

Traditional screening using chemicals or flow cytometry (FCM) alone is not sufficient to isolate the high glutathione (GSH)-producing yeast strains used in food production. Therefore, to improve screening efficiency, we investigated a combination of both methods. A mutated Saccharomyces cerevisiae strain was labeled with 5-chloromethylfluorescein diacetate and sorted by FCM according to emitted fluorescence intensity.

Protein kinase C delta plays a key role in cellular senescence programs of human normal diploid cells.

In the present study, we clarified that transforming growth factor beta (TGF-beta) induces cellular senescence in human normal diploid cells, TIG-1, and identified protein kinase Cs (PKCs) as downstream mediators of TGF-beta-induced cellular senescence. Among PKCs, we showed that PKC-delta induced cellular senescence in TIG-1 cells and was activated in replicatively and prematurely senescent TIG-1 cells. The causative role of PKC-delta in cellular senescence programs was demonstrated using a kinase negative PKC-delta and small interfering RNA against PKC-delta.

Complete deficiency of 5'-nucleotidase activity in Escherichia coli leads to loss of growth on purine nucleotides but not of their excretion.

Escherichia coli has many periplasmic phosphatase activities. To test whether it can take up and excrete purine nucleotides, we attempted to completely disrupt periplasmic 5'-nucleotidase activity. A 5'-nucleotidase activity was induced in ushA knockout mutant cells, which lack major 5'-nucleotidase activity, when they were grown with purine nucleotides as the sole carbon source.

Decreased tumorigenicity in vivo when transforming growth factor beta treatment causes cancer cell senescence.

We have previously reported that transforming growth factor beta (TGF-beta) triggers two independent senescence programs, 1) replicative senescence dependent upon telomere shortening and 2) premature senescence independent of telomere shortening, in the cell line of A549 human lung adenocarcinoma. In this study, we examined the possibility that cancer cell tumor phenotypes could be suppressed by forced senescence. We used A549 cells treated with TGF-beta for a long time (over 50 days), where senescence was induced in a telomere-shortening-dependent or an independent way.